Many types of dessert soup, featuring various main ingredients, are routinely consumed in Thailand as well as other places in Asia, especially the East and Southeast. Some of these dessert soups are served warm; some are served chilled or topped with crushed or shaved ice; some are great at any temperature. I have covered some of them here already. Remember pineapple in iced syrup (or the apricot version of it), glutinous rice pearls in sweet coconut cream, crunchy water chestnut dumplings in iced coconut syrup, or sweet sticky rice and durian in coconut cream? Even things that you don’t normally associate with dessert — let alone ice dessert — can be prepared in this manner, e.g. egg noodles. Sa-khu Cantaloupe (localized as khaentalûp), a chilled dessert ‘soup’ of chewy tapioca, juicy cantaloupe, and sweet and creamy coconut milk fits right in that pattern.
Once cooked, tapioca pearls become soft, translucent, sticky, and viscous. Sweetened with sugar and topped with creamy and slightly salty coconut cream topping, you get a comforting, warm, and gooey pudding that comes in countless variations depending on what other ingredients you add to the tapioca base to create different flavors and textures (corn kernels, young coconut meat, and taro are among the most common add-ins). The way tapioca pearls are used in this case, however, is atypical. The presence of this large amount of coconut milk breaks up the starchy “glue” that holds the cooked tapioca pearls together, causing the tiny beads to loosen, separate from one another, and float freely.
The end result is not much different from a chilled bubble tea. The only exception is that it’s served in a bowl instead of a tall see-through glass, that the tapioca pearls are lighter in color and much smaller, and that you go after the little pearls and the added melon balls with a spoon and not an oversized straw.
To make this dessert, you need raw Asian tapioca pearls (sa-khu) which are tiny opaque white (sometimes pink and green) beads, each about the same size of the head of a sewing pin. Tapioca pearls are inexpensive (the bag you see here cost me 75 cents) and are commonly found at most Asian grocery stores. Do not use the instant tapioca in the Jell-O aisle of the mainstream grocery stores; it does not work at all in this recipe.
As for the cantaloupe, make sure it’s fully ripe and sweet for bland melon makes this dessert sad. If you’re not a cantaloupe fan, you can use any type of sweet, juicy muskmelon. Honeydew works beautifully, as do Crenshaw and Korean melon (which I love). Watermelon is the only thing that doesn’t work; it’s too watery.
The last remark is about the coconut milk: Feel free to use any type of coconut milk you like [*]. You know how I’ve told you (here and there — on Twitter, Facebook, in my book, etc.) that when you make a Thai coconut-based curry, you should use full-fat coconut milk with no stabilizer, emulsifier, or added starch for best results? Forget that in this case. Even coconut milk made from coconut milk powder can be used in a pinch. Heck, in the absence of better alternatives, I would even use the type of coconut milk that comes in a cardboard carton which you find in most supermarkets’ refrigerators — you know, the type meant as a dairy substitute that would create disastrous results when used in a Thai curry. Fresh coconut cream, extracted from fresh mature coconut meat, is — believe it or not — not ideal in this case as without emulsification the fat tends to solidify when you chill or ice this dessert — which you will do before serving.
[*] You can use cow’s milk or a combination of cow’s milk and coconut milk. In fact, it seems most vendors of this dessert on the streets of Bangkok advertise that they use cow’s milk. For what it’s worth, I don’t much like coconut milk in this but prefer using 50% whole milk (cow’s milk) and 50% evaporated milk (not to be confused with sweetened condensed milk).
- 2 cups water
- ½ cup uncooked tapioca pearls
- About ½ cup of sugar, more or less to taste
- 1 cup coconut milk (low-fat is okay) or cow's milk or a combination of both, at room temperature
- ½ teaspoon salt (not optional; the salt makes a difference)
- 2-2½ cups ½-inch balls of cantaloupe or honeydew melon (or a combination of both), kept chilled
- 1 cup crushed ice, optional
- Put the water in a 1-quart saucepan; bring it to a boil, covered.
- Add the tapioca pearls and 1 tablespoon sugar to the boiling water; give it a stir to prevent clumping. Cover the saucepan and lower the heat just so the water is simmering instead of boiling furiously. After 5 minutes, give the tapioca another stir. Continue to cook until the tapioca pearls are translucent and the liquid becomes mucilaginous. This should take about 5 minutes longer. (The tapioca pearls will not become entirely clear; some will remain opaque white at the core even when they're cooked through. To be sure, taste a small spoonful to see if they're ready, i.e. soft yet chewy and no longer hard and gritty in the center.)
- Add the coconut milk and salt to the tapioca; stir to combine. While the mixture is still warm, add the remaining sugar to the pot, one tablespoon at a time, and taste as you go until the mixture is sweet enough. (If you plan on serving this with crushed ice, you need to may want to add more sugar to the mixture than you think prudent as the ice will melt into the soup and dilute it; what starts out as adequately sweet could end up bland in the process.)
- Once the taste is right and the sugar has fully dissolved, cool the cooked tapioca until it comes to room temperature. (You can use this time to prepare the melon, if you haven't done so.)
- When the tapioca has cooled, decide whether you would like to serve this dessert a) chilled or b) iced. If A, chill the tapioca mixture until very cold. Then divide it among 4 dessert bowls. Divide the melons among the 4 bowls. Serve chilled. If B, skip the chilling; simply divide the tapioca soup among 4 dessert bowls (large enough to hold twice the volume of each portion). Then divide the melon balls and crushed ice between the 4 bowls, stir, and serve immediately.